Sumber :
http://www.psdbox.com/tutorials/manipulation-secrets-3-shading-and-lighting/
(belajar b'ing dikit rekk)
Shadows are a very important aspect of any photo manipulation. Just as it happens with lighting effects, if the shadows are used the right way, you can end up with a stunning image. In this tutorial I will show you a few techniques I use to create realistic shadows and lights with Photoshop
The first step will be only theory to help you understand how lights and shadows work and on the following steps I will show you how to actually create the shadows.
1) Light source and shadow angles.
Before even starting to do anything on you image, you must decide whether you need shadows or not. To guide yourself you must first identify the main light source.